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View Full Version : neodymium magnets and glue



rmuell01
09-30-2011, 06:08 PM
Like Frank Ford, I love these magnets, especially the 1"x1/8" round. The two times I've glued them they create a white foam that dries very hard.
1. Aluminum was the metal I used
2. and a plastic flashlight

http://i178.photobucket.com/albums/w243/rmuell01/IMG_0020.jpg

I would glue each piece with some gorilla glue:

http://i178.photobucket.com/albums/w243/rmuell01/IMG_0022.jpg

the outcome is that the bond seems reduced, because the mags will come loose within a short period of time.

what do you use to attach neodymium magnets to various surfaces.

Rob

Iraiam
09-30-2011, 06:16 PM
I use cyanoacrylate (super glue or CA). The problem with gluing these magnets to stuff is they are usually nickel plated (or something similar). so the glue joint is only as strong as the plating.

The CA is strong enough that you pull hard enough on the magnet the plating will come off sometimes, I also use good CA, not the cheap Walgreens stuff.

Regnar
09-30-2011, 06:27 PM
You might want to try a piece of scrim cloth in-between. Your surfaces probably have very little imperfections and squeezing out the majority of your glue. The cloth will give some stand off and not squeeze it all out and allow the bond.

Rustybolt
09-30-2011, 08:20 PM
For regular temperatures I use an off the shelf two part epoxie and the magnets have held for years.In alum. For teps over 250 deg F we use a special potting epoxie that's good for 400 deg f.

Evan
09-30-2011, 08:29 PM
Gorilla glue is a urethane glue and the foaming in normal. It's good for some things, especially flexible items but otherwise I don't like the foaming action. Your best bet is epoxy intended for metal. As said, the plating is the weakest part of the bond. The plating is to prevent oxidation of the magnet material. You can sand off the plating and bond directly to the magnet for a much better bond. As long as the magnet isn't exposed to the air it will be fine.

Be careful when sanding. Do it by hand. The magnet alloy is very combustible, much like Misch metal (lighter flints).

lynnl
09-30-2011, 08:50 PM
I would reach for this stuff (gutter sealant), made by Amerimax:
http://www.homedepot.com/buy/building-materials-roofing-gutters/amerimax-seamermate-10-oz-gutter-sealant-116982.html

It takes a day or so to cure, but it's tough as all 'get out' when it does cure.
Sticks to any smooth surface. ...and hands and fingers!!

chipmaker4130
09-30-2011, 09:07 PM
I use E-6000. I get it at ACE hardware. It is very tough, flexible glue, sticks to most surfaces very well.

MichaelP
10-01-2011, 02:40 AM
I use epoxy glue from Big Box stores.

darryl
10-01-2011, 03:40 AM
Some kind of non-brittle epoxy would probably be one of the best answers. Cleaning off any oils, etc is going to make a difference. I use brake clean myself, and tissue paper to wipe it all clean without touching fingers to the surfaces being glued.

Of interest to me would be the different expansion ratios of the two parts. I don't know how aluminum compares to the magnet material, but I can imagine that it would have a higher expansion ratio. Flexible epoxy might be the best bet, although some compounds are much better on aluminum than others. PC-7 has worked well for me on al.

Gluing a magnet- I would also tend to make sure the glue forms around the edge of the magnet besides being between the magnet and the surface it's being glued to. I'm still talking epoxy- it should form a bit of a concave bead around the magnet as it flows up the edge.

Here's something I haven't done yet, though thought of it many times. For the best chance at keeping the magnet in place, form a circle of fiberglass cloth over the magnet and down onto the surface. Wet it all out well with the epoxy, and maybe use a short length of pvc pipe to form the cloth down over the magnet while the epoxy cures. If you do a neat job of cutting and placing the cloth, there won't be much to clean up afterwards- maybe a bit of excess epoxy before it starts to gel.

rode2rouen
10-01-2011, 08:25 AM
I use silicone RTV. A little dab'll do ya.
Works a treat!


Rex

Your Old Dog
10-01-2011, 08:36 AM
This isn't the answer for the op but while on the topic of gluing I'll toss it out there.

I once glued a nickel to a zippo lighter that stayed for 10 years or so. I prepped it with alcohol and used a rubbery brown stick sold in fishing supply places for repairing your waders from leaks. It was called "Magic Patch" and was applied with a match and melted on. It never got brittle and always stayed just a tad rubbery.

I'm just say'en....... :D

BMW Rider
10-01-2011, 12:13 PM
Gorilla glue is a urethane glue and the foaming in normal. It's good for some things, especially flexible items but otherwise I don't like the foaming action.

The problem with this type of glue is that you must have a very close fit between the parts since the foam has very little strength. Any gaps will be filled by foam and the bond will be far less than if the parts fit tightly.

rmuell01
10-01-2011, 12:23 PM
The magnet Was a bit dirty, I normally use some automotive dirt/greaser cleaner on anything I glue, I guess I was lazy.

I've got some E-6000, I'll try that first. but I think you all have some good ideas. thanks

rob

darryl
10-01-2011, 06:16 PM
From what I've read about E-6000, it will work as well as or better than you need it to for this application. Clean well the mating surfaces, especially get all the old glue off.

One of the 'tricks', though not really a trick, is to let the adhesive set BEFORE you test the strength of the bond. Common sense really, but it's tempting to defy this- human nature I suppose.

KEJR
10-02-2011, 08:44 AM
I just drill a slightly oversize hole and use a special metal glue called loctite. I too made up some holders like Frank Ford does out of brass. In retrospect I'll probably use Aluminum as the brass chips I was picking out of my hair all night :)